captioning sponsored by macneil/lehrer productions >> woodruff: on the anniversary of a mass shooting in arizona, and in the aftermath of the newtown school massacre, anti- gun advocates today ramped up their campaign. good evening. i'm judy woodruff. >> ifill: and i'm gwen ifill. on the newshour tonight, we look at the drumbeat for action, and get an update on the second day of hearings for the suspect in the colorado theater shootings. >> woodruff: then we examine the investigation into the 9/11 attacks on the u.s. consulate in benghazi, libya, when four americans were killed, as the sole suspect in custody is released. >> ifill: spencer michels reports on the boom in online teaching and its impact on traditional liberal arts education.